Zeolites are microporous crystalline aluminosilicate materials that have pore sizes ranging from about 0.3 nm to 1 nm. Because of their uniform, molecular-sized pores they can separate molecules based on their size, shape and polarity. They can therefore act as “molecular sieves” and are often described as such. Membranes made of zeolites and molecular sieves possess good thermal and chemical stability and thus have a number of practical applications, for example in the separation of gases and liquids and as selective barriers for sensors. In addition, zeolite materials have catalytic properties that means that they can be employed as catalysts in reactors such as packed-bed and membrane reactors.
The desirability of incorporating zeolite materials and structures in microsystem architectures has also been recognized. Chemical processes such as separation and reaction can benefit from miniaturization. Faster mass and heat transfer rates owing to the larger surface-to-volume ratios, and the well-defined flow and mixing patterns are some of the advantages of a microchemical system. Miniaturization also enables the design of smaller and more compact units, and allows for rapid design implementation due to the easier scale-up through replication.